Altitude switch



May 25, 1948. J. J. ZELLER mm. 2,442,108

ALTITUDE swITcH Filed Sept 27, 1944 2 Sheets-Sheet 1 INVEN TOR5.

May 25, 1948.

J. J. ZELLER EIAL ALTITUDE SWITCH Filed Sept. 27, 1944 2 Sheets-Sheet Z NVE TOR-5. Josef J7 el 6);

Patented "my 25, 1948 ALTITUDE SWITCH Jose! J. Zeiler, Detroit, and William 1!. Woods, Garden City, Micin. assignors to Square 1) Company, Detroit, Mich., a corporation of Michigan Application September 27, 1944, Serial No. 555,940

3 Claims. (Ci. zoo-as) This invention relates to a pressure operated electric switch and more particularly to a switch automatically operated in response to change in altitude pressure.

In the operation of aircraft, it is desired to effect operation of devices or secure warning signals at predetermined values of altitude pressure. One specific example of this lies in the automatic cutting in and out of the engine supercharger at predetermined altitude settings.

The object of the invention is the provision of an improved form of simple and reliable altitude pressure operated electric switch.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure 1 is a view of an altitude pressure switch according to the present invention, with the cover broken away to show internal parts.

Figure 2 is a partial detailed view of the operating mechanism taken on the line II--II of Figure 1.

Figure 3 is a partial detailed sectional view on the line III-HI of Figure 2, with certain parts shown in elevation.

The altitude switch, according to the present invention, comprises an outer casing having a removable cover :2 sealably attached thereto in airtight relation, An opening, not shown, is provided into the casing for the attachment of a connection to the static line of a pitot static tube. Within the casing is disposed a bracket ii within which is supported a standard snap switch of any desired form having an operating pin Within a bushing 6 in the bracket is is sliciahly supported an operating pin i adapted to be engaged by an abutment 9 upon the outer or" a plurality of serially connected aneroid capsules ii and it. Within the bracket upon a pin is pivotally mounted a oifuocatecl lever i l carrying. a web 65 adapted to he engaged by a pin and, in turn, to engage the pin ii to effect the operation of the switch 3. The lever it has an end web it adapted to engage a pin it of a differential control indicated generally at it, The end of the lever i l opposite the web it is provided with a counter-Weight it. The bracket 3 is supported within the enclosure i upon posts by means of studs 22.

The differential adjustment is shown in partial section in Figure 1 in which the pin ii is slidahly mounted for longitudinal movement and is biased toward its extended position by a spring 23, the tension on which may be adjusted by means of stud 24. The position of the extended position of the pin relative to th web I6 is ad- Justable by means of rotation of the threaded casing 25 which has a locking stud 26 for holding it in its adjusted position. The adjustment of the diflerential I8 is such as to provide for the web I6 engaging the pin I1 and becoming loaded with the tension of spring 23 prior to effecting actuation of the switch 4; however, in the reverse direction, the adjustment is such that the web 16 will leave the pin I! so that it is no longer loaded by the spring 23 before the switch 4 snaps to its opposite position. This loading oi. the operating lever ll in only one direction will determine the differential of pressure between the ON and OFF positions of the switch.

The aneroid capsules 9, ii and 52 are connected together so that their movements are additive and the resultant movement of pin i is the sum of the individual movements of the aneroids. The aneroids are mounted by means of a stud 2i secured to the left hand face of the anerold a as viewed in Figure l. Upon this stud, between two locking nuts 23, is disposed a U shaped bimetallic member 2'9 having a pair of pins Zil adjacent the free ends of its leg which engage with the abutment 8 to retard its movement and provide for a temperature compensation for the movement of the aneroids. It will be seen that this compensation will vary with the fissure of the bimetallic element and also with the position of the abutment ii (and, hence, the inclination of pins Eli). 'lihis temperature arrangement compensates for the error in the movement of the aneroids due to changes in the temperature to which they are exposed. The mounting stud 2? is threaded into a supporting sleeve 32 adjustahly and slidahly received within a hub in the switch. casing and biased by return spring so toward the left, as viewed in Figure 1. An adjust lug nut S5 is threaded in the hub and has a point hearing on the sleeve til to effect longitudinal movement of the sleeve and adjustment bodily of the aneroid group. an arm is mounted rigid with the stud 2'? and sleeve lit and engages a pin 3? in the switch enclosure to prevent rotation of the aneroiol assembly.

To the switch casing are attached the mounting brackets 38 and st for mounting the switch in the structure with which it is to be associated. An electrical outlet plug is indicated at 46 for the connection of circuit wiring.

In the operation of the switch, as the altitude pressure decreases, the aneroids 8, Ii and i2 expand and move the abutment 8 toward the right, as viewed in Figures 1 and 3. As the abutment 8 engages the pin 1, it will cause rotation of the lever I4 about its pivot 13 in a clockwise direction. As the lever l4 rotates, the web 15 effects forward movement of the pin 5 actuating the switch 4. Prior to the operation of the switch 4, the web l8 engages the pin I! and further movement of the lever [4 to actuate the switch 4 is accomplished under the loading of the differential spring 23. Upon sufiicient movement of the aneroid capsules, switch 4 will be operated to secure the desired operation of the device which it controls. Upon a decrease in altitude pressure, the reverse action takes place except that the web l6 leaves the pin I1, so that it is no longer operated on by the loading of spring '23, prior to reverse actuation of the switch 4.

The altitude pressure at which the operation takes place or the range adjustment of the device is effected through adjustment of the screw 35 which moves the aneroid assembly bodily toward or away from the pin 7. The adjustment of the threaded sleeve 25 determines the proper cooperation of web IB and pin I! in the pick up and release of spring loading on the lever I4 in the operations of the switch 4. The adjustment of the stud 24 determines the amount of spring loading applied by pin I1 to an operating lever' l4.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

'1. In a pressure responsive device, a sealed'enclosure, means connecting said enclosure to a pressure condition in response to which the device is to respond, an electric switch within said enclosure having an operating element, a pivoted lever for moving said element, means for moving said pivoted lever in response to change in said pressure condition comprising a sealed aneroid capsule, means mounting said capsule in said enclosure for movement bodily toward and away from said lever to adjust the range of pressure at which the device is responsive, and means controlling the differential of pressure at which the device responds including a spring bias loading said pivoted lever in only one direction of switch operation.

2. In a pressure responsive device, a sealed enclosure, means connecting said enclosure to a pressur condition in response to which the device is to respond, an electric switch within said enclosure, an aneroid capsul within such enclosure for effecting operation of said switch, means mounting said aneroid capsule for adjustment bodily in the direction of its expansion and contraction movement whereby to adjust the range of pressure at which the switch is operated, said switch operating at one pressure value upon increase in said pressure condition and operating at a second pressure value upon decrease of said pressure condition, and means for varying the pressure difference between said pressure values comprising means for resiliently loading the movement of the aneroid capsule adjacent one only of said pressure values.

3. In a pressure responsive device, a sealed enclosure adapted to be connected to a varying pressure condition, an electric switch within said enclosure having an operating element, a pivoted lever for moving said element, means for moving said pivoted lever in response to change said pressure condition comprising a sealed aneroid capsule, means mounting said capsule in said enclosure for movement bodily toward and away from said lever to adjust the range of pressure at which the device is responsive, said switch being operated at one pressure value upon increase in said pressure condition and being operated at a second pressure value upon decrease in said pressure condition, and means for varying the difference in pressure of said pressure values comprising means for applying a spring bias to said lever adjacent one only of said pressure values.

JOSEF J. ZELLER. WILLIAM H. WOODS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,447,076 Hamilton Feb, 27, 1923 1,802,486 Summers Apr. 28, 1931 2,031,837 Kollsman Feb. 25, 1936 2,116,960 Brown et al. May 10, 1938 2,150,771 Kollsman Mar. 14, 1939 2,315,137 Shaw Mar. 30, 1943 2,316,009 Martin ct al. Apr. 6, 1943 2,366,566 Shivers Jan. 2, 1945 2,373,041 Martindell Apr. 3, 1945 FOREIGN PATENTS Number Country Date 841,470 France Feb. 8, 1939 

